I need help with explaining these two curves. The left, Fig. 11-1(a), is a strong acid, HCl, titrated with a strong base, NaOH. The right, Fig. 11-1(b), is acetic acid titrated with NaOH as well.
I understand that for Fig. 11a, the different initial pH for the different concentrations are due to HCl dissociation, which is concentration dependent. But there are a couple things I don't understand about the curves.

1. Why are the initial pH of the acetic acid so similar to each other before the equivalence point if their concentrations are all different?

2. For all analytes in both figures, why is the amount of titrant the same to reach the equivalence point?

3. After equivalence point is reached, why do the curves behave similarly for both figures?